[U-Boot] [PATCH 2/3] sunxi: video: Add support for external DAC enable pin

[Chen-Yu Tsai]

The external DAC for VGA output might have either a power or reset
control pin that needs to be pulled up, as is the case on the
Hummingbird A31.

Signed-off-by: Chen-Yu Tsai <wens at csie.org>
---
 board/sunxi/Kconfig           |  8 ++++++++
 drivers/video/sunxi_display.c | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index bce270e..e9a6b3c 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -315,6 +315,14 @@ config VIDEO_VGA_VIA_LCD
 	LCD interface driving a VGA connector, such as found on the
 	Olimex A13 boards.
 
+config VIDEO_VGA_EXTERNAL_DAC_EN
+	string "LCD panel power enable pin"
+	depends on VIDEO_VGA_VIA_LCD
+	default ""
+	---help---
+	Set the enable pin for the external VGA DAC. This takes a string in the
+	format understood by sunxi_name_to_gpio, e.g. PH1 for pin 1 of port H.
+
 config VIDEO_LCD_MODE
 	string "LCD panel timing details"
 	depends on VIDEO
diff --git a/drivers/video/sunxi_display.c b/drivers/video/sunxi_display.c
index 47d820d..1052af2 100644
--- a/drivers/video/sunxi_display.c
+++ b/drivers/video/sunxi_display.c
@@ -813,6 +813,23 @@ static void sunxi_drc_init(void)
 #endif
 }
 
+#ifdef CONFIG_VIDEO_VGA_VIA_LCD
+static void sunxi_vga_external_dac_enable(void)
+{
+	int pin;
+
+	/*
+	 * Start with backlight disabled to avoid the screen flashing to
+	 * white while the lcd inits.
+	 */
+	pin = sunxi_name_to_gpio(CONFIG_VIDEO_VGA_EXTERNAL_DAC_EN);
+	if (pin != -1) {
+		gpio_request(pin, "vga_enable");
+		gpio_direction_output(pin, 1);
+	}
+}
+#endif /* CONFIG_VIDEO_VGA_VIA_LCD */
+
 static void sunxi_engines_init(void)
 {
 	sunxi_composer_init();
@@ -860,6 +877,7 @@ static void sunxi_mode_set(const struct ctfb_res_modes *mode,
 		sunxi_lcdc_tcon0_mode_set(mode);
 		sunxi_composer_enable();
 		sunxi_lcdc_enable();
+		sunxi_vga_external_dac_enable();
 #endif
 		break;
 	}
-- 
2.1.4